I have a 3-way light switch that I just replaced with a new illuminated one (glows when off). The light inside the switch is pulsating, like a heartbeat! I thought it was maybe a defective switch and changed it again with another new illuminated one, but still the same flickering. So it's definitely not the switch. What else would it be?
Additional context, this is part of a 4-way circuit in my hallway, including two 3-way switches and one 4-way switch. The lights turn on/off correctly, despite the flickering illuminated switch. And it's just one switch. I didn't change any of the wiring or terminal connections - just swapped old light switches for new ones.